Meconium-stained amniotic fluid linked to postcesarean SSI

SAN DIEGO – Meconium-stained amniotic fluid may increased risk of surgical site infections following a cesarean delivery, results from a large analysis showed.

Surgical site infection (SSI) occurs in 3%-9% of patients who have a cesarean delivery, and many require hospitalization or further surgery, lead study author Andrea Snyder, MD, PhD, said at the annual clinical and scientific meeting of the American College of Obstetricians and Gynecologists. Risk factors for SSI included chorioamnionitis, obesity, preeclampsia, preterm premature rupture of membranes, nulliparity, or emergency cesarean. Current management for avoiding SSIs includes prophylactic antibiotics, antiseptic skin, and vaginal prep.

Doug Brunk/Frontline Medical News

Dr. Andrea Snyder

Meconium-stained amniotic fluid (MSAF) occurs in 12%-15% of all deliveries, Dr. Snyder, of the department of obstetrics and gynecology at Ohio State University, Columbus, noted. “It is known to be associated with maternal infections including chorioamnionitis and endometriosis,” she said. “It is suspected that MSAF could be associated with SSI; however, few studies have been done.” One study from 1984 showed that MSAF was significantly associated with SSI (Am J Infect Control. 1984 Feb;12[1]:19-25). “However, this study was done prior to the routine administration of preoperative antibiotics for cesarean deliveries,” Dr. Snyder said. “Other studies since that time have either not shown an association between MSAF and SSI or have not separated SSI from postpartum endometriosis.”

In an effort to test the hypothesis that meconium-stained fluid is an independent risk factor associated with an increased risk of postcesarean SSI, she and her associates evaluated a subset of 25,220 women from the Maternal-Fetal Medicine Units Network cesarean registry who were treated at 19 different institutions. Their mean age was 27 years, they were all attempting labor or induction of labor, were all singleton pregnancies, and all had cesarean deliveries.

Of the 25,220 patients studied, 5,883 (23%) had MSAF. The researchers found that the incidence of SSI was 11.9% among patients who had MSAF, compared with an incidence of 8.9% among patients who did not, a difference that reached statistical significance (P less than .001). After using a multivariable logistic regression model to control for confounders including chorioamnionitis, diabetes, intrauterine pressure catheter placement, tobacco use, length of labor, length of rupture, preeclampsia, and obesity, the association between MSAF and SSI persisted (odds ratio, 1.25; confidence interval, 1.12-1.39; P less than .001).

Advantages of the study, she said, include the fact that it was a large population of patients treated at multiple institutions, “so it should be very generalizable to most practices. We also controlled for many known factors associated with SSI.” Dr. Snyder acknowledged certain limitations of the study, including the fact that the data do not show causation and that there is no further information about the SSIs. “Were those associated with meconium less or more severe SSIs?” she asked. “Does the increase in risk confer an increased risk of severe infectious morbidity? Where do we go from here and what do we do with this information? At this point we don’t have any way of preventing meconium.”

A 2014 Cochrane review found that, while prophylactic antibiotics for patients with MSAF did not decrease the risk of postpartum endometriosis, it did decrease the risk of chorioamnionitis. “But would it help decrease the risk of SSIs? We have no idea,” Dr. Snyder asked. “Would continuing antibiotics after delivery help reduce wound infections? We don’t do that routinely in a C-section, but maybe that would make sense for patients that are higher risk.” She reported having no financial disclosures.